Most prior art oscillating sprinklers provide a constant water flow to the sprinkler nozzles during the entire stroke of the sprinkler. The typical oscillating sprinkler must produce streams that reach great distances horizontally from the sprinkler in order to water a selected, approximately rectangular, watering area. However, because the water flow to the nozzles is substantially constant during the entire oscillation stroke of the sprinkler, the vertical height of the water streams from the nozzles when the nozzles direct the streams nearly perpendicular to the ground is almost the same distance as the horizontal length reached by the streams. FIGS. 1A-1B show the normal end-view and side-view water stream profiles, respectively, and FIG. 1C shows the watering area pattern, of a typical prior art oscillating sprinkler 100 as the sprinkler arm 106 completes an oscillatory arc. FIG. 1A shows a diagrammatic end view of the watering stream profile. The profile of the “throw” of the water streams (which includes their height and/or length) approximates an arc 102. The height of water streams near the zenith of the arc 102 can be problematic, because even light winds tend to carry a significant portion of the higher streams of water out of the desired spray area (while lower streams of water are affected by wind, they are not carried as far out of the spray area as higher streams). This can increase water waste due to loss by evaporation and often produces an uneven watering area. In addition, water is wasted by being directed to areas that the user does not intend to water. FIG. 1B depicts a side view of a water stream profile 112 when the water streams from the sprinkler arm 106 are vertical. The top portion of this side view of water stream profile 112 also approximates an arc.
FIG. 1C illustrates a top view of a normal watering area pattern—without any wind—of a typical prior art oscillating sprinkler 100 as the sprinkler arm 106 completes an oscillatory arc. The watering area pattern approximates an elongate oval 108. A typical area to be watered (e.g., a garden or yard) is usually more rectangular (e.g., phantom line rectangle 110). As a result, it is desirable to provide a watering pattern that is more rectilinear, thereby directing the water more efficiently to the area a user desires to water rather than dispensing water on “out-of-bounds” areas or leaving corners of a rectangular area unwatered.
U.S. Pat. No. 4,860,954 (the '954 Patent) discloses an oscillating sprinkler with a throttling mechanism provided to cyclically throttle the water flow to the nozzles to provide an aesthetically pleasing undulating spray pattern of the water streams. However, the '954 Patent does not systematically throttle water streams based upon their angle to or height from the ground in a manner that addresses the problem caused by winds carrying high water streams out of the desired spray area.
Thus, there is a need for an oscillating sprinkler that is capable of emitting water streams that effectively water a desired watering spray area, but that have a controlled vertical height, thereby reducing or minimizing undesirable effects caused by wind.